Rahu was working with King Snarr and the other fire giants of Flamefall Tower, as well as the drow exarch Lolestra and her minions, but reconsidered whatever diplomatic offer he was making when the Shields of the Sorrowfell arrived. In exchange for a moment alone with Bezaldooz, he explained the giants’ mission and told the Shields how to stop it.

Then he disappeared. I wonder what that was all about?

Image retrieved from http://forgottenrealms.wikia.com/wiki/File:Rakshasa-5e.png on April 2, 2018.